1 - you figure your total # of hours per day that you need
2 - you figure out what the legal & allowable minimum # of staff is allowed to work and for how long
3 - using the number of hours of coverage - M-F 0800- 1800 10 hour day

1 person can work 8 - 10 hours per day.

so 1 person is the minimum staff

4 - you take into consideration - meal breaks, lunch etc, off time etc
5 - so you double the number to 2 minimum
6 - then you look at the call volume and other actions the staff is going to do
that would boost your staff numbers
the rest you guess.

If yuou go to university and take management course.. is there not a course on human resources